China economic upturn threatens emissions gains.

An uptick in China’s economy after a four-year slowdown in growth threatens to reverse improvements in greenhouse gas emissions that had helped keep global levels flat for three years.

China’s economy grew at an annual rate of 6.9 per cent in the first quarter this year, its fastest in 18 months, according to official data. Commodity prices recovered last year after a four-year slump, while Chinese steel consumption rose after three years of declines following its 2013 peak. 

The economic revival has contributed to a rise in smog in northern China and the southern manufacturing heartlands after three years of improving air quality and falling coal consumption, according to provincial government data tracking tiny particles in the air known as PM2.5 — particles with a diameter of less than 2.5 micrometres. 

Air quality suffered a marked deterioration in the first quarter of this year compared with the same period of 2016, particularly in Hebei, the industrial province surrounding Beijing. Shanxi, where the coal and steel industries had been particularly hard hit by the slowdown, showed the greatest rebound, with PM2.5 levels 32 per cent higher than the year before.

The data have raised questions over whether China’s flattening emissions of the past few years are a result of policies to clean up its air and comply with the Paris agreement on climate change or simply the silver lining to an economy that was performing far worse than official data had suggested. A drop of 1 per cent in the country’s emissions last year, combined with lower emissions from the US, had helped stabilise global emissions for the third year in a row in 2016. 

“The huge jump in Beijing’s [air pollution] levels has already made meeting the air quality target for this year almost a mathematical impossibility,” said Lauri Myllyvirta, a Greenpeace campaigner in Beijing.

An acceleration in economic growth creates a greater increase in pollution from heavy industry. When the economy slows, smaller factories that survive on thin margins and burn dirtier coal are likely to shut first but these resume operations when the economy improves. In other words, the fluctuations in pollution levels are more extreme than those in growth driven by heavy industry.

Those northern provinces seeing a revival in pollution this year had all experienced steep drops in coal, oil and steel output and sharp slowdowns in growth in recent years.

Making matters worse, the slump in coal demand has triggered the expansion of the highly polluting coal-conversion industry, which turns the commodity into motor fuels, gas or chemicals. 

The technology became profitable because of the low cost of coal compared with state-set floor prices for gas and motor fuels. The coal-to-gas industry has helped meet China’s goals for converting cities to gas, but without reducing the national dependence on coal. 

Converting coal into gas in China’s less densely populated frontier regions and transporting it to eastern cities could also avert 20,000-41,000 premature deaths a year because it would result in less localised air pollution from coal-burning in large conurbations, according to research by scientists at Princeton University and Peking University published this week. 

But coal-to-gas plants under construction would increase China’s annual carbon emissions by about 1.5 per cent, based on 2016 emissions levels, the study found.

Another study released by Greenpeace this week found that if all current plans for converting coal to chemicals came to fruition, they would add about 4 per cent to China’s emissions levels by 2020. 

Follow Lucy Hornby on Twitter: @HornbyLucy